Cast muffler



March 12, 1963 E. M. JOBSON 3,

' CAST MUFFLER Filed Aug. 10, 1959 2 Sheets-Sheet 1 INVENTOR. EDWARD M. JOBfiON W|LSON,LEWIS MEAE March 12, 1963 E. M. JOBSON CAST MUFFLER 2 Sheets-Sheet 2 Filed Aug. 10, 1959 M M Q iVdr 7 5 z Z INVENTOR. EDWARD M. JOE SON WILSON,LE.WIS MEAE Unite This invention relates to mutiiers for internal combustion engines, and more particularly to an improved mufiler formed of east shells, preferably die cast and having suit-able deflecting bafiles to permit expansion and cooling of the exhaust gases under conditions whereby resonance and other undesirable noises are minimized.

It has been customary heretofore to fabricate mutllers of sheet metal members, generally steel, welded together to provide a casing within which suitable battles and tubes are positioned to permit the expansion of exhaust gases flowing from an inlet to a discharge end of the muffler. In operation, as the exhaust gases flow through the muflier, heat is absorbed from the gases and the gases are permitted to expand under conditions whereby noise is mufiied. The fabrication of mufiiers of these types has been expensive because of the need for using relatively expensive and intricate tooling, required to insure the securing of the various elements together in the desired configurations.

Mufiiers formed of steel are objectionable in use because they rust quickly when subjected to the corrosive action of the exhaust gases flowing therethrough and the corrosive action of the salt solutions and acids splashed on the mufller from the roadways. This is particularly true in wintertime when large quantities of salt or other chemicals are used to prevent the accumulation of ice on the roadways.

An object of my invention is to provide an improved muffler having a plurality of die cast shells adapted to be interlocked together, and wherein suitable exhaust gas deflecting batfies are provided within the shells to insure proper deflection of the exhaust gases to insure adequately mufliing the engine noises.

Another object of my invention is to provide a cast mufiier having sufficient metal in areas subjected to high heat concentrations to absorb heat and dissipate it without permitting the mufiler to be subjected to suflicient heat concentrations to melt or undesirably soften the muffier.

A further object of my invention resides in the provision of a die cast muiiier having symmetrical shell portions which may economically be cast and secured together to provide a substantially gas-tight shell.

Still another object of my invention is to provide a cast mufller having calculated increased thicknesses of section in the areas subjected to high heat concentrations from the exhaust gases flowing into the muflier to provide a thermal absorption and dissipating area capable of absorbing and dissipating heat without melting or softening to an undesirable degree the metal of which the muffier is formed.

Another object of my invention is to provide a die cast muflier having a plurality of gas deflecting baffles nested within symmetrical die cast shell members having suitable interlocking edge configurations which may be employed to permit ready assembly of the shell members to provide a substantially gas tight chamber.

A further object of my invention is to provide a cast muffler formed of substantially symmetrical shell members having wall members which extend slightly nonparallel relative to each other and which may be forced into substantial alignment for clamping engagement relative to each other to induce a prestressing of the walls Patented Mar. 12, 1963 of the muflier member to insure a gas-tight connection between the shell members.

Yet a further object of my invention is to provide an improved muffler formed of symmetrical die cast shell members having a plurality of longitudinally spaced partition and support members therein to receive and support exhaust gas deflecting tube members proportioned and located to direct exhaust gases to follow a tortuous path as they flow from the muflier inlet to the outlet thereof, heat being absorbed from the exhaust gases and the gases being permitted to expand to induce the desired sound muffling and silencing action to eliminate resonant and other undesirable noises.

Still a further object of my invention is to provide a cast mufiler having suitably positioned exhaust gas defleeting members and expansion chambers which facilitate the tuning of the mufller to a particular engine to insure operation of an engine exhaust system below a predetermined noise level free from undesirable resonance factors.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification and wherein like reference characters designate corresponding parts in the several views.

In the drawings:

FIG. 1 is a perspective view of my improved cast muflier.

FIG. 2 is a longitudinal plan view of the mufller illustrated in FIG. 1 with the upper shell removed.

FIG. 3 is a sectional view taken substantially on the line 3'3 of PEG. 2 looking in the direction of the arrows.

FIG. 4 is a perspective view, partly in section, of one of the tube members illustrated in FIG. 2.

FIG. 5 is a sectional view taken substantially on the line 5--5 of FIG. 2 looking in the direction of the arrows.

FIG. 6 is an enlarged fragmentary sectional view taken substantially on the line 6--6 of FIG. 1 looking in the direction of the arrows and illustrating the bayonet type attaching mechanism employed to secure the symmetrical shell members together.

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Referring now more particularly to the drawings, it will be noted that two symmetrical shell members 10 and 12 are employed. As illustrated in FIG. 2 the shells 10 and 12 are formed with end walls 14 and 16, and each shell member has a desired plurality, such for example as three, spaced partition and support walls 18, 2 0 and 22 formed therein.

The partition wall 18 is as illustrated of greater thickness than the support and partition walls 20 and 22 respec tively. The increased thickness of the wall 18 provides a sufiicien-t mass of metal to absorb and dissipate the heat from the exhaust gases without allowing the wall to become sufficiently high in temperature that it would be undesirably softened or melted. M

Each of the shell members 10 and 12 may be formed with longitudinally interrupted internally slotted side flange members 24 and a longitudinally extending groove 25 formed on one side, and longitudinally interrupted laterally extending flange members 26 and an outwardly extending tongue 27 cooperating with the slotted flange members 24 to form a so-called bayonet type securing connection between the shell members 10 and 12. The longitudinal spacing of the slotted flange members 24 of the shell members 10 and 12 is proportioned to provide between each adjacently positioned pair of flanges a space 23 for the reception of the alternately spaced flange members 26 f the other shell member 12 or 10.

It will thus be apparent that to assemble the shell members and 12 the flange members 26 of one shell memher are positioned in the spaces 28 between the adjacently positioned slotted flange members 24 of the other of the shell members. It will be noted that the shell members 10 and 12 arespaced longitudinally relative to each other a distance equal to one spacing 28 at this stage of the assembly. The shell members 10 and 12 are then shifted longitudinally relative to each other to align bolt receiving apertures 30 and 32 in the end walls 14 and 16 Whereupon the flange members 26 lie within the grooves 25 of the flange members 24 and the tongue projections 27 extend into the grooves 25 to provide a substantially gastight joint. Retaining bolts 34 are then inserted through the aligned apertures, and nuts 36 are secured to the bolts to fasten the shell members 10 and 12 securely together.

It will be understood that if desired the flange members 26 and the internally slotted flange members 24- may be suitably contoured to provide a camming action to draw the confronting shells 10 and 12 together into intimate leakproof engagement as they are shifted longitudinally to the assembled position.

If desired the confronting side walls of the shells 10 and 12 may be initially deformed slightly such for example as to provide confronting convex surfaces which abut on assembly and may be straightened out into substantial parallelism when the shell members 10 and 12 are forced together by the application of compressive forces in the as sembly of the mufller.

A plurality of spaced longitudinally extending heat dissipating and strengthening flanges 38 are formed on the upper and lower surfaces of the shell members 10 and 12. The heat dissipating flanges can if desired be of any desired proportions and may extend over the entire surface of the shell members 10 and 12.

It will of course be apparent that the shell members 10 and 12 may be of any convenient shape to fit within a desired configuration within the automobile chassis. My improved muffler may thus be elongated or shortened as desired, the thickness and width dimensions varying within reasonable limits to insure embodying within the muffler the desired cubical capacity to provide the necessary ex haust gas expansion, resonating and sound deadening chambers suitably proportioned relative to each other. Also it will be apparent that it is not necessary that the side or the bottom and top walls extend parallel relative to each other-because the muffler can be of tapered configuration or it can be of generally circular configuration to fit substantially any suitable space that may be available within the vehicle. Where it can conveniently be arranged it is desirable that the section 10 and 12 be symmetrical to avoid the necessity of making more than one set of tooling.

The end walls 14 and 16 have cut-out portions 42 and 44 to receive and engage the end of an exhaust pipe adapted to be clampingly engaged by suitable fittings with the exhaust manifold of an engine. The pipe 40 is preferably supported at its inner end in a cut-out portion 46 formed in the support wall 20. The mufller is provided at its opposite end with a tail pipe 48, clampingly engaged in the cut-out portion 44 formed in the rear end wall 16, and in the rearmost partition wall 22.

A pair of exhaust gas transfer tubes 50 and 52 are mounted in preferably rounded-cut-out portions in the support walls 20 at their forward ends, and in cut-out portions in the intermediate partition 18 at their rear ends. The exhaust gas transfer tubes 50 and 52 are thus mounted in substantially parallel relation with the exhaust gas inlet pipe 40. As illustrated in FIG. 2 the transfer tubes 50 and 52 have axially extending struts 54 and 56 which con- 1 meet short resonating tubes 58 and 6b with the transfer tubes 56 and 52 respectively. The short resonating tubes 58 and 60 are mounted in cut-out portions in the partition wall 22 which also has a rounded cut-out portion to receive and support the forward end of the exhaust gas outlet or tail pipe 48.

It will be noted, as shown in FIGS. 2 and 3 that the partition 18 may have a thickened section 61 to provide an enlarged area or mass of metal in the path of exhaust gases flowing from the exhaust pipe 40 to absorb heat from the exhaust gases and dissipate it without becoming heated to the point where the metal would melt or become softened. If desired the partition 18- may have a reinforcing section 62 which is formed for example of heat resistant material. It may however if desired be formed of the same material of which the body of the muffler sec tions it and 12 are formed, such for example as die cast aluminum. Where the section 62 is formed of dis-similar material as metal, the reinforcing member may be positioned in the mold as an insert to be bonded into the shell members 11 and 12 during the casting operation.

As shown in FIG. 4 the transfer tubes 50 and 52 may, if desired, have an axially disposed helical baffle members 64 positioned therein to induce the exhaust gases flowing through the transfer tubes 5t: and 52 to flow about a tortuous or extended path whereupon heat is absorbed from the exhaust gases, and the peak vibrations which are capable of producing undesirable imparting or resonating noises are dissipated as the exhaust gases flow through the transfer tubes.

The bafile members 64 may be formed of sheet material, preferably of a Width substantially equal to the diameter of the transfer tubes 50. This sheet material may be twisted to take the form of a helix whereupon the exhaust gases are forced to follow a spiralling or cork-screw shaped path of travel.

In assembling the components of my improved muffler, one of the shell members 10 or 12 is supported as shown in FIG. 2. The exhaust gas inlet tube 40 is placed therein, being supported in the cut-out'portions in the front wall 14 and in the partial partition or support Walls 20 as illustrated. The exhaust gas transfer tubes 50 and 52 are placed in the cut-out portions formed in the partial partition or support walls 20 and in the central partition 18 with the struts 54- and 56 positioning the short resonating tubes 58 and 6% in the cut-out portions formed in the partition 22. The exhaust gas outlet tube or tail pipe 48 is positioned in the cut-out portions in the partition 22, and in the cut-out portion 44 formed in the rear end wall 16.

The matching shell member 10 or 12 is then inverted relative to the first-mentioned shell member. and it is placed thereon, the various tubes 46, 50, 52, 58, 60 and 48 projecting into the similarly configurated cut-out portions of the respective walls of the shell member which is then applied. The two shell members are of course assembled in a slightly staggered relation longitudinally to permit the interrupted side flange members 26 to project between the lugs having the internal slots of the flange members 24 of the other shell member.

The two shell members are then compressed to force the confronting walls into substantial parallelism and to firmly engage the various pipe members. The laterally extending side flange members 26 of one shell member are thus positioned to lie within the slots of the flange members 24 of the other shell member. It will of course be apparent that the cooperating flange members may be designed with angular inclinations to permit the members to readily engage each other and exert a tensioning force to urge the shell members firmly into intimate gas leak free engagement as the shell members It} and 12 are shifted longitudinally relative to each other to align the locking flange members 26 within the internal slotted flange members 24. The muffler shell members are thus compressed firmly together to engage the pipe sections and to insure tight engagement along the peripheral edges of the cooperating shell members. This tight engagement insures gas leakproof contact between the cooperating shell member s, and accordingly clamps the various pipes securely in their respective partition members.

-It will be understood that if desired suitable gasket material may be interposed between the shell members, and between the partitions and support members and the various pipe members to prevent leakage of exhaust gases.

After the shell members have been shifted axially to the assembled position the bolts 34 are projected through the aligned apertures in the end walls of the shell members. The nuts 36 may then be applied to clamp the assembly and to maintain the shell members against longitudinal shifting. V

In the operation of my improved muffler it will be understood that exhaust gases collected from the engine in the exhaust manifold are directed through a suitable pipe connected in any desired manner with the exhaust gas inlet pipe 40. The exhaust gases flowing into the muffler defined by the two shell members it and 12 flow into a chamber 66 where the gases impinge on the thickened section 61 of the partition wall 18 which provides a mass of metal sufficient volume to absorb and dissipate the heat without subjecting the partition to a suificient degree of concentrated heat to melt it or to cause it to soften to an undesirable degree. The exhaust gases flowing into the chamber 66 are deflected by impingement on the wall 18 and expand in the chamber 66. The partially cooled gases flow forwardly toward the end wall 14 and flow through the open spaces 67 between the support walls or partial partitions 2t) and the inlet pipe 40 and the transfer tubes 50 and 52. The total area of the spaces 67 is preferably a little larger than the area of the inlet pipe 40 to permit the gases to flow into the forward expansion chamber 68 without being subjected to undesirable restriction which would cause back pressure.

It will be noted that the support walls or partial partition 20 which supports the rear end of the pipe 40 and the forward ends of the pipes 56 and 52 has relatively narrow flanges 69 extending inwardly from the side walls of the shell members and 12 to reinforce and strengthen the shell members. The exhaust gases are permitted to further expand in the chamber 68 and the gases enter the forward ends of the transfer tubes 50 and 52. The area of the transfer tubes 50 and 52 is somewhat larger than the area of the inlet pipe 40 to avoid the development of undesired back pressure. Where the helical baffles 64 are employed the exhaust gases are induced to swirl around within the transfer tubes 50 and 52 as they flow rearwardly through the transfer tubes into a chamber 76 positioned between the intermediate partition 18 and the partition 22 supporting the forward end of the tail pipe 48 and the resonating tubes 58 and 60 illustrated as being carried by the transfer tubes 50 and 52.

A portion of the exhaust gases flows outwardly from the transfer tubes 50 and 52 through the side openings 72 between the struts 54 and 56 into the chamber 70 which communicates with and permits the exhaust gases to flow into the forward end 74 of the tail pipe 48. The exhaust gases are thus discharged from the chamber 70 through the tail pipe 48 for discharge through any convenient tail pipe arrangement through which exhaust gases are dissipated to the atmosphere.

It will be apparent that when an engine is started a portion of the gases flowing through the transfer tubes 50 and 52 flow through the resonating tubes 58 and 60 into an expansion and resonating chamber 76 positioned for example adjacent the rear end wall 16 of the shell members 10 and 12. As shown by the direction of the arrows 78 exhaust gases flow into and out of the resonating chamber 76. When the pressures built up in the chamber 76 reach a predetermined pressure the exhaust gases flowing through the transfer tubes 50 and 52 impinge on the 6 partially compressed gases through the resonating tubes 58 and 60. The exhaust gases flowing out of the transfer tubes 50 and 52 thus abut a mass of pressurized gases in the chamber 76 thereby providing a resonating action to muifle undesirable sound producing impulses.

It will be understood that my improved muffler may be of virtually any desired shape to fit within substantially any convenient space where a sufiicient cubical muffler area proportional to the displacement and compression ratio of the engine is available within the vehicle chassis.

A desired number of internal partion and support walls such as 18, 2t and 22 may be employed and they may be positioned at appropriate locations to permit the dedesired expansion and resonating efifect of the exhaust gases as they flow through the muffler from the exhaust gas inlet pipe 40 to the tail pipe 48, the gases being progressively cooled and expanded as they flow through the muffler to provide a desired muffled and sound deadening action to insure desired commercially acceptable results. The heat from the exhaust gases is dissipated to the atmosphere through the heat radiating fins 38.

While I prefer that my improved muffler will be formed by die casting operations, it will be understood that it may advantageously be formed by other methods of casting such for example as by shell, permanent mold or other casting techniques, whereby desired consistency and homogeneity of the alloy is maintained.

It will also be apparent that the transfer tubes 50 and 52 with their resonating tubes 58 and 60, as well as the exhaust inlet pipe 4%) and the exhaust outlet or tail pipe 48, may be formed in any desired manner, such for example as by extruding aluminum or other suitable alloy. It will also be apparent that these tubes and pipes may if desired be of different materials from that which the shell members 10 and 12 are formed. For example steel tubes may be used in die cast shell members 19 and 1-2. It will be apparent that if desired die cast walls may be assembled within the labyrinth to produce the same result.

Briefly summarized my improved muffler contemplates the use of a die cast aluminum casing or box designed to radiate, dissipate and otherwise effect the discharge of heat from exhaust gases to the atmosphere. The use of castings, preferably die cast or extruded aluminum is preferable to the use of sheet aluminum due to the necessity of increasing the mass of alloy in the areas required to receive and conduct heat under conditions whereby it can be quickly and efficiently radiated to the atmosphere. This also permits unlimited flexibility of design in the positioning of interior baifles, channels, walls, ports, chambers, resonating cavities, passages, ducts etc., to embody in the muffler the desired functional characteristics, and to permit the muffler to be designed to fit within suitable spaces available in the vehicle.

The use of die cast or other cast configurations permits of the insertion within the mold of heat resisting material to be bonded into the casting to absorb and dissipate heat from areas of high heat concentration. It will also be apparent that the design or configuration of fins, channels, bafiies, passages, flow chambers, ducts, tubes, etc., can advantageously be proportioned by die casting or other casting techniques to conduct or dissipate to the outside atmosphere, heat from the exhaust gases by inducing the atmospheric air to flow over, impinge against or around the heat concentration areas to aid in carrying 01f this heat.

The cast condition further allows flexibility of design of the inlet and outlet pipes. Also it will be apparent that front, back, sides, top and the bottom of the casting is readily available for the dissipation of heat.

It will also be apparent that the use of steel tubes for the inlet pipes transfer tubes and possibly the outlet pipe permits greater flexibility of design. The inside of various tubes may have spiral, helical or cork-screw configurations formed therein by metal baffles to force the 7 gases to travel a greater distance inside the pipes, tubes, channels, etc. to dissipate heat and induce mufiiing and sound deadening actions to aid in the dissipation due to longer contact with the tube, etc.

To summarize, attention is directed to the fact that the prevention of melting of the aluminum metal when in use in a mufiier, can only be accomplished by heat control through the application of what I term the mass thermal absorption technique. By this-I mean designing a sufficient mass of metal in the heat concentration areas to absorb and conduct from the impinging exhaust gases heat at a rate fast enough to prevent the localized concentration of heat to reach a temperature high enough to melt or undesirably soften the metal. The formation of an aluminum or other suitable alloy muflier is only feasible from an economic point of view through the casting processes, and the formation of such a muffier permits the use of aluminum, with its corrosion resistant qualities, to be applied to the manufacture of mufiiers, a much desired application previously not possible.

The heat developed in the exhaust gases of an internal combustion engine is dependent on the speed at which the engine is operated, the number of cylinders in the engine, the compression ratio, the octane number of the fuel and other factors. My improved muflier is proportioned to provide a sufficient mass of metal 61 in the partition 18 to function as a thermal reservoir to absorb heat from the exhaust gases impinging thereagainst and dissipate the absorbed heat through the walls of the mufiier at a sufficiently rapidrate that the partition is maintained below its melting temperature when the engine is operating to peak speed or torque output. It will be apparent that the other Walls of the muffler can be contoured to provide desired masses of metal proportioned to the heat to which various portions of the muffler are subjected.

It will be apparent that muiiiers formed by my improved techniques are adapted for all permissive uses, not only on engines used in motor vehicles but for all other applications.

I claim:

1. In a mufiier,

identical half shells defining a hollow interior cavity,

each said shell comprising a generally fiat plate with opposed longitudinal sides and opposed ends extending in a common direction from the periphery thereof,

the longitudinal sides having complementary interlocking means along their terminal edges,

each of the ends having a recess centrally thereof,

heat radiating means on the exterior of said plate,

a transversewall between said end walls,

said transverse wall having a passage therethrough,

said transverse wall having greater heat-absorbing properties than the remainder of the half shell and connected thereto in heat-transfer relation to transfer heat to said radiating means,

and interconnecting fastening means on the half shells for holding the rnufiier together,

whereby the half shells are connected in gas seal relation by engaging the complementary interlocking means when said halves are assembled in mirror image array and the fastener means are interconnected.

2. In a muffler half shell,

a substantially fiat plate with opposed sides and ends extending in a common direction away from the periphery,

one of the sides having a male lock along the terminal edge and the other side having a female lock along the terminal edge,

each of the ends having a recess centrally thereof,

heat radiating means on the exterior of said plate,

a transverse wall between the said ends,

said transverse wall having apassage therethrough,

and said transverse wall having a greater heat-absorb ing-property than the remainder of the half shell and connected thereto in heat-transfer relation to transfer heat to said radiating means. 7

References Cited in the file of this patent UNITED STATES PATENTS 360,315 Lockhart Mar. 29, 1887 622,615 Fleming Apr. 4, 1899 1,055,708 Case Mar. 11, 1913 1,622,692 Wendling Mar. 29, 1927 2,109,220 Noblitt et al. Feb. 22, 1938 2,166,408 Hoyle July 18, 1939 2,196,920 Hoyle Apr. 9, 1940 2,334,204 King Nov. 16, 1943 2,788,078 Reindl Apr. 9, 1957 2,924,293 Sprague Feb. 9, 1960 2,956,637 Lemmerman Oct. 18, 1960 2,958,389 Dererner Nov. 1, 1960 FOREIGN PATENTS 221,071 Great Britain Sept. 4, 1924 312,943 Great Britain June 4, 1929 702,370 France Jan. 20, 1931 721,292 France Dec. 12, 1931 918,062 Germany Sept. 16, 1954 

1. IN A MUFFLER, IDENTICAL HALF SHELLS DEFINING A HOLLOW INTERIOR CAVITY, EACH SAID SHELL COMPRISING A GENERALLY FLAT PLATE WITH OPPOSED LONGITUDINAL SIDES AND OPPOSED ENDS EXTENDING IN A COMMON DIRECTION FROM THE PERIPHERY THEREOF, THE LONGITUDINAL SIDES HAVING COMPLEMENTARY INTERLOCKING MEANS ALONG THEIR TERMINAL EDGES, EACH OF THE ENDS HAVING A RECESS CENTRALLY THEREOF, HEAT RADIATING MEANS ON THE EXTERIOR OF SAID PLATE, A TRANSVERSE WALL BETWEEN SAID END WALLS, SAID TRANSVERSE WALL HAVING A PASSAGE THERETHROUGH, SAID TRANSVERSE WALL HAVING GREATER HEAT-ABSORBING 